Highly reactive materials are those agents that undergo rapid chemical change causing exothermic or other self-accelerating reactions when subjected to heat, impact, friction, light, catalysts, or other initiation. These agents are materials that will detonate or deflagrate.

[collapsed title=List of some Highly Reactive Materials]

Highly reactive materials encompass (but are not limited to): 

• Air-reactive chemicals (e.g., palladium or platinum on carbon, platinum oxide, Raney nickel) 
• Metal hydrides (e.g., lithium aluminum hydride, sodium borohydride) 
• Cryogenic materials/liquefied gas, supercritical fluids (e.g., oxygen, nitrogen, helium) 
• Highly water-reactive chemicals (e.g., aluminum bromide, metal hydrides, phosphorus pentachloride, tin tetrachloride, titanium tetrachloride) 
• Explosive dusts (e.g., magnesium powder, zinc dust, carbon powder, flowers of sulfur) 
• Explosives, other (e.g., diazomethane, hydrogen peroxide, hydrogen, chlorine, polymerizing acrolein, trinitrotoluene) 
• Organic peroxides (e.g., acetyl peroxide, benzoyl peroxide) 
• Organometallic chemicals and active metals (e.g., trimethyl gallium; sodium, magnesium, lithium, potassium) 
• Oxidizing agents (e.g., halogens, oxyhalogens, peroxyhalogens, permanganates, nitrates, chromates, persulfates, peroxides) 
• Perchloric acid and perchlorates (e.g., sodium perchlorate) 
• Peroxide-forming chemicals (e.g., acrylonitrile, dioxane, ether, isopropanol, tetrahydrofuran) 
• Polymerization reactions (e.g., acrylate monomers) 
• Polynitro organic chemicals (e.g., picric acid, dinitrophenylhydrazine, methyl nitronitrosoguanidine) 
• Pyrophoric chemicals (e.g., boranes, white phosphorus, alkyl metals such as n-butyllithium and dibutyl magnesium) 
• Shock-sensitive and other unstable chemicals (e.g., acetylides, azides, nitro compounds, organic nitrates, perchlorates). 
• Solutions such as piranha, nitol, aqua regia, and electropolishing solution.

Many of the above classes of materials overlap with other hazard types (e.g., organometallics may be pyrophoric). The list is intended merely to provide guidance for determining whether this section applies to the research in your lab. Exact classification is not necessary.

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[collapsed title=General Rules for Working with Processes That Involve Highly Reactive or Explosive Materials]

NOTE: A process may involve more than one type of hazard for example, compounds may be reactive, may cause system over pressurization, and may be used with vacuums (e.g. highly reactive materials, high-pressure systems, vacuum systems).  Be sure to address all the hazards that apply to your process.  

1. All persons working with highly reactive material in Georgia Tech laboratories shall receive training in the hazards of the material and in how it is to be used in a particular process from the PI or a senior lab staff member.  This training is to be documented.
2. All labs using highly reactive materials will complete a pre-start up safety review (Appendix I) and have a Lab safety Plan (Appendix H) prior to obtaining the material.  These will be used to produce a Standard Operating Procedure (SOP) as soon as reasonably possible.   
3. New processes involving pyrophoric material must be pre-approved by the GT CESC prior to material purchase.  (Contact EHS at 404-894-4635 for help in completing this process.) 
4. All purchase requests for  pyrophoric and water reactive materials are routed through Buzz Mart to EHS for approval.
5. Heating will be by heating tapes, mantles, or water, steam, or oil baths which will be utilized in such a way as to contain explosions whenever possible.
6. Prior to starting an experiment involving potentially explosive material, the lab Safety Plan will be reviewed by the entire lab staff to ensure that all persons know what to do, were an explosion to occur.  Additionally, it will be to ensure that provisions have been made to contain the entire reaction mixture, should a mishap occur. A template for a lab safety plan can be found in Appendix H.  
7. Dry ice-solvent baths may not be not used for reactive gases. 
8. Hot liquids may not brought into sudden contact with lower-boiling liquids. 
9. Boiling chips may not be added once the heated liquid has exceeded its boiling point. 
10. The areas where highly reactive chemicals, high-pressure, or vacuum equipment are used shall be posted with signs to warn colleagues of potential danger. 
11. When a reaction becomes uncontrollable, turn off the heat, the addition of reagents shall be suspended, nearby lab workers shall be notified, and the chemical fume hood sash shall be closed until the temperature has dropped. 
12. When a potentially hazardous reaction is attempted, total quantities of reactants shall be limited to 0.5 g in the reaction vessel. 
13. It is the responsibility of the researcher to ensure that emergency equipment is on hand for reactions that could runaway violently prior to beginning the experiment, and rechecking that all the equipment is still in place prior to repeating the experiment.   
14. When appropriate, tongs will be used to manipulate highly reactive chemicals to prevent exposure of any part of the body to possible injury (e.g., when immersing sodium metal in solvents, handling heated crucibles, or removing weighing dishes from ovens). 

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[collapsed title=Operational Practices for Specific Classes of Reactives]

The categories listed below are not exhaustive and do not necessarily cover all possible circumstances that must be controlled. 

[collapsed title=Piranha]

Piranha solution is used frequently in the microelectronics industry, to clean, for example, photoresist from silicon wafers. It is used in scientific research to make highly hydrophilic surfaces. It is sometimes used to passivate glassware prior to doing sensitive chemical reactions. Unlike chromic acid solutions, piranha will not contaminate glassware with heavy metal ions.

There are two different piranha solutions:  The most common is the acid piranha: a 3:1 mixture of concentrated sulfuric acid (H2SO4) with hydrogen peroxide (H2O2). The other is base piranha: a 3:1 mixture of ammonium hydroxide ( NH4OH) with hydrogen peroxide (H2O2). Both are equally dangerous when hot, although the reaction in the acid piranha is self-starting whereas the base piranha must be heated to 60 degrees to initiate.

Acid piranha is a mixture of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2), used to clean organic residue off of substrates. Because the mixture is a strong oxidizer, it will remove most organic matter, and it will also hydroxylate most surfaces (add OH groups), making them extremely hydrophilic (water compatible).

[collapsed title=Lab and Personnel Requirements]

Piranha is considered a “Highly Reactive Substance”.  As such, all labs making or using piranha must have:  

• A Lab Safety Plan (See Appendix H for a template)
• A Pre-start up safety review (Appendix I) which can be use to develop:
• A standard operating procedure
• All labs using piranha need to keep a written copy of this Section in the lab with an attached signature sheet  

In addition, all labs using piranha must have:

• A fume hood
• The required PPE:
• Lab coat or clean room garment
• Acid resistant apron with long sleeves
• Safety glasses
• Face shield
• 6 ml nitrile gloves
• Heat resistant gloves

All persons working in GT labs are required to dress appropriately per the GT Appropriate Attire and Personal Protective Equipment Policy including:

• Long pants
• Shirt that completely covers the torso
• Shoes that completely enclose the foot (no open toes or backs), preferably of a material that can be wiped clean
• Hair tied back

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[collapsed title=Making Piranha]

• Piranha may only be made in a fume hood or, if in a clean room, an exhaust- ventilated chemical bench.
• Piranha solutions may only be made on the day that they are to be used.  They may not be made in advance and may never be stored.
• Whenever handling piranha, only use glass containers (preferably Pyrex) as piranha will attack some plastics and can get hot enough to melt others
• Containers used to make piranha should be 3X larger than the volume of piranha that you intend to make.
• Containers holding piranha must be very clearly labeled and have RTK compliant warning sign, visible by any user working under the hood.  Signs must be posted at all time to indicate that the vessel contains piranha mixture. 
• Mix the solution in the laboratory hood with the sash between you and the solution. Wear the required PPE. 
• Always add the peroxide to the acid or the base.  When making acid piranha, the H2O2 is added immediately before the etching process because it immediately produces an exothermic reaction with gas (pressure) release.
• Any variation from the standard 3:1 acid: peroxide mixture require written approval in advance, from the Principle Investigator.
• Peroxide used to make piranha may not exceed 49% concentrations as higher concentrations may cause an explosion. 
• Piranha solution is very energetic and potentially explosive.  It is very likely to become hot (more than 100°C).  Handle with care using appropriate thermally protective gloves.

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[collapsed title=Using Piranha]

• Substrate should be rinsed and dried before placing in a piranha bath. Piranhas are used to remove photoresist and acetone residue, not the compounds themselves.
• The hot (often bubbling) solution will clean organics off of substrates, and oxidize/hydroxylate most metal surfaces. Cleaning usually requires about 10 to 40 minutes, after which time the substrates can be removed from the solution.
• Anything removed from the solution should be rinsed with a large amount of deionized water. The substrates should now be hydrophilic, which is easily verified by ensuring that the rinse water is wetting (spreading out over) the substrate.
• Immersing a substrate (such as a wafer) into the solution should be done slowly. This is to prevent a thermal shock that may crack the substrate material.
• Leave the hot piranha solution in the fume hood in an open container until cool. Never store hot piranha solutions.  Piranha stored in a closed container will likely explode.
• Adding any acids or bases to piranha or spraying it with water will accelerate the reaction. 
• Mixing hot piranha with organic compounds may cause an explosion.  This includes acetone, photoresist, isopropyl alcohol, and nylon.
• Wash bottles containing organic compounds should be removed from the hood before making piranha

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[collapsed title=Piranha Waste Disposal]

• The primary hazard from storage of piranha waste is the potential for gas generation and over pressurization of the container when the solution is still hot. If you store a hot solution in an air tight container, it will explode!
• Prior to storing the waste piranha solution, it must be left in an open container in order to cool down for several hours (overnight).
• It is your responsibility to make sure that the open container is very clearly labeled and left in a safe area for overnight cool down. Fill in your name and contact information on the label.  It is your responsibility to make sure that you return the next morning to bottle up the cooled waste.

• Once cooled down, the solution can be transferred into a closed glass container for waste storage. The container must be very clearly labeled with the solution name and composition and must include VERY VISIBLE warning signs not to add any other types of chemicals.
• Use EHSA to generate a waste card (http://ehsa.gatech.edu/ehsa) and request a pick up. Contact the HazMat Manager if you have any questions.

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[collapsed title=Emergency Procedures]

Runaway reactions

• Evacuate area
• Pull fire alarm
• Call GT police at 404-894-2500
• Remain on scene to provide information to first responders

Exposures to Piranha

• In case of large exposure, the victim should be removed from the contaminated area, placed under a safety shower while GT police are contacted  at 404-894-2500 (4-2500 or 911 from a GT land-line)
  • All contaminated clothing should be removed immediately with appropriate gloves and safely discarded.
• In case of contact with the skin, the affected area must be immediately rinsed with large amounts of water for at least 15 min.
  • Call GT Police at 404-894-2500. Tell them that you will need an ambulance.
• In case of contact with the eye, irrigate the eye for at least 15 minutes, keeping the eyelids apart and away from eyeballs during irrigation. Place ice pack on eyes until reaching emergency room.
  • Call GT Police at 404-894-2500. Tell them that you will need an ambulance.
• In case of inhalation, it may irritate the respiratory tract. 
  • Conscious persons should be assisted to an area with fresh, uncontaminated air (always send a helper, who has a cell phone, out with the victim- do not let the victim go out alone). 
  • Seek medical attention in the event of respiratory irritation, cough, or tightness in the chest. 
  • Symptoms may be delayed
  • Serious, life-threatening effects may manifest 4-5 hours after exposure.  
  • Call GT Police at 404-894-2500. Tell them that you will need an ambulance.

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[collapsed title=Combustible/ Explosive Dusts]

Many people are unaware that the most mundane of powdery materials (dusts) can ignite and even explode under the right set of conditions:  A dust explosion is the fast combustion (deflagration) of dust particles suspended in the air in an enclosed location. Coal dust explosions are a frequent hazard in underground coal mines, but dust explosions can occur where any powdered combustible material is present in an enclosed atmosphere.  There are four necessary conditions for a dust explosion: A combustible dust; the dust is suspended in the air at a high concentration; there is an oxidant (typically atmospheric oxygen); and there is an ignition source. A fifth favorable, but not strictly necessary condition is that the dust be confined.

Many materials which are commonly known to oxidize can generate a dust fires or explosions, such as coal, sawdust, and magnesium. However, many otherwise mundane materials can also lead to a dangerous dust cloud such as grain, flour, sugar, powdered milk and pollen. Many powdered metals (like aluminum and titanium), can form ignitable/explosive suspensions in air.  On Feb 8, 2008, a dust explosion in Port Wentworth, GA, leveled a sugar refinery, killed 6 workers, and injured 44 others.  In May of 2009 a mostly empty jar containing metal and resin powders caught fire in the hand of a Georgia Tech researcher while she shook it to loosen the powder stuck to the side of the jar; she was not injured.

For ignition to occur, dust must also consist of very small particles, presenting a large  surface area, allowing it to support combustion. Dust is defined as powders with particles less than about 500 micrometers in diameter, but finer dust will present a much greater hazard than coarse particles by virtue of the larger surface area.

[collapsed title=Common sources of ignition]

• electrostatic discharge
• friction
• sparking from machinery or other equipment;
• hot surfaces
• fire

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Different dusts will have different combustion temperatures and dust of various types will either suppress or elevate this temperature in relation to the stoichiometric concentration of the dusts. It is necessary that sufficient energy, generally either thermal or electrical, be applied to trigger combustion. Due to the small volume in relation to the large surface area, combustion can then proceed very rapidly and the flame front can also travel quickly. For example, 1 kg of powder, 120 µm in diameter will have a surface area of 50 m² or 540 sq ft. Due to the thermal expansion of the gas, the pressure increases. In an enclosed space this leads to the over pressurization of the “container” which could be a jar in a laboratory or an entire building, causing it to burst or “explode”.  

[collapsed title=General Rules for Working with Oxidizable Dusts]

• All care shall be taken to avoid aerosolizing the oxidizable particulates.
• Suspensions of oxidizable particles shall be handled wet, when this is not possible, they shall be handled under inert atmospheres.  
• The airborne particulates shall not be exposed to ignition sources. 
• Adequate local exhaust ventilation or a fume hood shall be provided to control the concentration of airborne dusts; dilution (room) ventilation is not acceptable.  

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[collapsed title=Organometallics and Pyrophoric Chemicals]

In December of 2008, a young researcher at UCLA was badly burned while working with tertiary (t) - butyl lithium.  She died as a result of her burns a few weeks later. T-butyl lithium and other organometalic compounds are very reactive; many are also pyrophoric and ignite spontaneously upon exposure to air. Due to the potential risks involved in working with organometallics and pyrophoric materials, it is especially important to assure that all possible steps have been taken to prevent mishaps while handling these materials:

Pyrophoric materials are on the GT Restricted Purchases list (http://www.ehs.gatech.edu/chemical/pre_approval.pdf ): please complete the Pre-notification form and contact GT EHS Laboratory and Chemical Safety Manager before acquiring any pyrophoric material that you have not used previously at Georgia Tech. The acquisition must be approved by the Georgia Tech Chemical and Environmental Safety Committee before you may proceed.

To help with the approval process, please provide a copy of your Standard Operating Procedures for working with the material in question which describe

• The training the people who will handle it have received
• Where (building, room) it is to be used
• Engineering controls to be used (fume hoods, glove box)

Additional rules regarding the use of pyrophoric gases can be found in the Georgia Tech Dangerous Gas Safety Program.

[collapsed title=General Rules for Working with Organometallics and Pyrophorics]

• Where organometallics are used, Class D fire extinguishers shall be provided. 
• All pyrophorics shall be used and stored in an inert atmosphere (e.g., under nitrogen or argon). 
• Glove boxes used with pyrophoric materials are to be vented to the exhaust ventilation system (fume hood exhaust), not to room air or the room air exhaust system.
• Pyrophorics shall only be handled in a glove box or fume hood
• Prior to starting work with a pyrophoric material, remove all flammable  and combustible material from the fume hood/glove box that is not associated with the procedure you are about to accomplish
• Prior to starting a transfer of a liquid pyrophoric material, the stock bottle must be firmly clamped in place. 

Transfers of liquid materials involving more than 10 mL shall only be accomplished by the double tipped needle method.

• Regulators shall be set correctly to prevent glassware from being over pressurized with nitrogen or argon. 
• To avoid spills resulting in fires, breakable glass bottles shall be stored inside a rubber or plastic bottle carrier. 
• Personal Protective Equipment for working with organometallics and pyrophorics shall include 100% natural fiber clothing and Flame Resistant lab coat, appropriate gloves, and safety glasses or goggles. (See the GT Personal Protective Equipment and Appropriate Attire Policy.)

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[collapsed title=Organic Peroxides and Peroxide-forming Chemicals]

Organic Peroxides and Peroxide forming chemicals are classified as Potentially Explosive Chemicals (PECs) under Chematix, the computer program used by Georgia Tech to track and manage chemicals.  An organic peroxide is any organic (carbon-containing) compound having two oxygen atoms joined together (-O-O-). This chemical group is called a "peroxy" group. The main hazards related to organic peroxides are their fire and explosion hazards. Most undiluted organic peroxides can catch fire easily and burn very rapidly and intensely. This is because they combine both fuel (carbon) and oxygen in the same compound. Some organic peroxides are dangerously reactive. They can decompose very rapidly or explosively if they are exposed to only slight heat, friction, mechanical shock or contamination with incompatible materials. See the section on Chemical Storage for more information on peroxide forming chemicals and how EHSA can help you manage them safety.

[collapsed title=General Rules for Working with Organic Peroxides and Peroxide-forming Solvents]

• Organic peroxides and peroxide-forming materials shall be stored blanketed with an inert gas (nitrogen or argon) protected from and stored away from heat and light. 
• Keep peroxide formers cool but do not refrigerate.  Refrigerator temperatures may freeze out or precipitate the peroxide.
• Ceramic, or plastic, spatulas shall be used with organic peroxides. Metal spatulas must never be used. 
• Never purchase more than “immediate use” quantities of organic peroxides and peroxide formers.
• Never re-package organic peroxides in glass containers with screw caps or glass stoppers.
• Never submit peroxides to friction, grinding, or other forms of impact.  
• Organic peroxides should be diluted with inert solvents such as mineral oil to reduce their sensitivity to heat and shock. 
• Liquid organic peroxides are must never be allowed to freeze, as phase changes increase the sensitivity of these compounds to shock and heat. 
• Peroxide-forming solvents shall be checked for the presence of peroxides upon receipt from the manufacturer and after every 3 months of storage (EHSA will send a reminder). Testing may be conducted with instantaneous peroxide indicator strips.  If positive, material should be treated to remove the peroxide or wasted out.  A label should be affixed to the container to record that the material has been checked- and when.
• Peroxide-forming solvents shall also be checked for the presence of peroxides prior to heating.  
• EHSA will automatically send an expiration notice for peroxide forming chemicals one year after purchase.  Peroxide formers for which there is no planned use should be disposed of through Environmental Health and Safety.  
• EHSA expiration notices on materials which have been checked for crystals or tested may be “reset”.  Contact EHS for assistance at  ehsa@gatech.edu     
• Before distilling any known or suspected peroxide former, check it carefully for peroxide.  If any is present, eliminate it by chemical treatment or percolation through a suitable adsorbent, or add a high-boiling aliphatic hydrocarbon (such as mineral oil) to prevent the peroxide from concentrating to a dangerous level.  Never distill a peroxide former to dryness.

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[collapsed title=Working with Ether Used as an Anesthetic]

• Like other peroxide-formers, ether must be stored in a cool, dry, well-ventilated place, out of direct sunlight. It must be purchased in small containers, no more than is absolutely necessary. It shall be stored as far back on a shelf as possible to minimize the potential for falling. It should be easy-to-reach to prevent knocking against the container. 
• Ether shall be checked for peroxides quarterly.  It is recommended that ether be discarded 6 months after opening/1 year after purchase. Peroxide test strips are available from Lab Safety Supply and other reputable safety supply distributors (e.g., Fisher, Baxter).   
• Both unused ether supplies (older than 6 months) and ether known to contain peroxides must be disposed of through EHS. Evaporation of ether in a chemical fume hood is forbidden by law, except for residual amounts in an empty can. Disposal down the drain is also unlawful. 
• Animal carcasses containing ether must be stored in flammable safe refrigerators or freezers where ether vapors cannot ignite. 

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[collapsed title=Oxidizers]

Oxidizing materials are liquids or solids that readily give off oxygen or other oxidizing substances (such as hydrogen peroxide, nitrates, nitrites, and permanganates). They also include materials that react chemically to oxidize combustible (burnable) materials; this means that oxygen combines chemically with the other material in a way that increases the chance of a fire or explosion. This reaction may be spontaneous at room temperature or may occur under slight heating. Oxidizing liquids and solids can be severe fire and explosion hazards. See the Section on Storing Chemicals- Oxidizers for more information.

[collapsed title=General Rules for Working with Oxidizing Agents]

• Oxidizing agents must be kept separate from reducing materials, metals, ordinary combustibles and from each other. 
• Oil baths shall not be used when oxidizing agents are present. 

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[collapsed title=General Rules for Working with Perchloric Acid and Perchlorates]

• Laboratories must inform EHS before beginning work with hot processes involving perchloric acid.
• Organic materials shall be digested with nitric acid before the addition of perchloric acid. 
• Heating perchloric acid outside of a perchloric acid hood is strictly forbidden Operations involving heating perchloric acid above room temperatures (i.e., during acid-based digestion) shall be accomplished only in a wash-down laboratory chemical fume hood of noncombustible construction. 
• Chemical fume hoods in which perchloric acid is heated are inspected frequently by EHS for the accumulation of perchlorates. Deposits are saturated with water and removed. 
• Perchloric acid is never used near, nor stored on, wooden shelves. 
• Perchloric acid bottles shall be stored in secondary containers (trays, beakers) made of glass or ceramic. 
• Perchloric acid and perchlorates shall not be stored with organic materials. 
• Perchloric acid shall not be heated with sulfuric acid. 

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[collapsed title=Polynitro compounds]

Acquisition of explosive polynitro compounds is restricted under Georgia Tech Rules and may involve permitting under Federal Regulations and/or Georgia State Fire Safety Regulations, even if limited to “Laboratory Quantities”.  Please contact EHS at 404-894-4635 before purchasing or agreeing to accept these materials from outside Georgia Tech or from other Georgia Tech researchers.

General Rules for Working with Polynitro Organic Chemicals and Shock-sensitive or Unstable Compounds

• Poly nitro compounds and shock- sensitive compounds may only be purchased in immediate use quantities.
• The stock of polynitro compounds shall be stored separately from other lab chemicals. 
• Stock of poly-nitro compounds shall be inspected quarterly for degradation or dehydration, as these compounds may become more shock-sensitive with age (Chematix will automatically send a reminder) . 
• Polynitro compounds shall be disposed of through EHS when the project for which they were purchased ends, or at 1 year after purchase. They may not placed in storage for future use, as they may become more hazardous over time. 
• When polynitro and shock-sensitive compounds are moved, they must be handled by the container bottom and never by the cap or lid. 
• Picric acid shall be kept hydrated or kept in solution to reduce sensitivity. It may never be allowed to dry out completely.
• Picric acid containers must be inspected to ensure that it is fully hydrated quarterly (EHSA will send a reminder)
• Picric acid shall be disposed of through EHS after the project for which it was purchased has ended or after 1 year (EHSA will automatically send a reminder)
• Solid sodium azide, in quantities above 25 g, should be dissolved when it arrives in the lab. Solutions of sodium azide do not pose the danger of shock-sensitivity associated with the solid form; however, the hydrazoic acid generated when the azide is dissolved is extremely toxic. Therefore, the solution is always prepared inside a chemical fume hood. If not dissolved, solid azide must be stored in a locked cabinet. 

Teflon or other nonmetal spatulas must be used with solid sodium azide due to its reactivity with metals.

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